There are many safety syringe designs available today. Some of these designs have a sleeve or a sheath that will cover the needle after it has been used. Some typical designs with sleeves or sheaths are Z. M. ROEHR et al U.S. Pat. No. 3,008,570, Z. M. ROEHR U.S. Pat. No. 3,107,785, BARTNER, et al U.S. Pat. No. 3,895,633, G. K. BURKE U.S. Pat. No. 3,306,291, GYURE et al U.S. Pat. No. 4,300,678, WINSTEAD HALL U.S. Pat No. 4,356,822, SAMPSON U.S. Pat. No. 4,425,120, LARSON U.S. Pat. No. 4,639,249, HARBAUGH U.S. Pat. No. 4,655,751, STRAUSS U.S. Pat. No. 4,664,654 , BRAGINETZ U.S. Pat. No. 4,666,435, SPENCER U.S. Pat. No. 4,702,738, MILORAD U.S. Pat. No. 4,702,739, SPENCER U.S. Pat. No. 4,801,295, PONCY U.S. Pat. No. 4,816,022, and HUGHES U.S. Pat. No. 4,840,619.
Other designs have a retractable needle such as WELTMAN U.S. Pat. No. 3,306,290, and DENT U.S. Pat. No. 4,392,859. These designs do not have a means whereby the needle is extended from the syringe and held in place in a positive and rigid position in order to first inject the needle prior to injecting the medication. Most of these designs have one major purpose and that is to prevent the spread of infectious diseases such as aids, hepatitis or other diseases from an accidental injection with a contaminated needle, into others after the needle of the syringe was inserted into a patient with the above mentioned disease. These various designs all work well up to a degree, but they all fall short of their intended purpose during the act of covering the needle, or removing the needle.
All of these designs require at lease two hands to operate. The use of two hands to cover the contaminated needle is most unsatisfactory in that during the act of placing a second hand on the syringe the person holding the syringe in one hand may be bumped and accidentally inject the needle into their other hand before it can grasp the syringe. Other accidental jabbings or injections can happen in an ambulance where just as a person tries to grasp the contaminated syringe, the ambulance can hit a bump in the road causing the person holding the syringe to accidently stick another person or themselves with the contaminated needle. The need has developed for a syringe that will cover the contaminated needle with the use of only one hand.